1. Technical Field
This invention pertains to semi-rigid protective covers for portions of vehicles such as aircraft having surfaces that are particularly susceptible to damage from dirt, sand, ultraviolet radiation, chemical agents, and other airborne particulate hazards. In particular, the covers can be used to protect aircraft canopies from hail, blowing sand, dirt, dust, chemical agents, or ultraviolet radiation.
2. Description of Related Art
Vehicles in transit or storage are generally subject to a variety of environmental hazards. These hazards can have an adverse effect on surfaces, instruments, or components of a vehicle and thereby diminish or destroy the effectiveness of the vehicle in performing its intended mission. A surface that is susceptible to environmental degradation is the canopy of an airplane or helicopter. Erosion, which includes cracking, scratching, pitting, chafing and chemical alteration, of the canopy clear surfaces (by wind-blown sand, for example) can cause serious impairment of a pilot's field of vision outside the aircraft and thereby reduce or eliminate the fitness of the machine for flying, absent repair or replacement of the clear cover. Such damage can occur while an aircraft is be4ing shipped aboard another vehicle (by ship, rail or truck, for example), while it is parked between missions, or while it is in storage. Other surfaces present similarly serious potential risks. Delicate instruments, such as radar equipment, missile guidance systems, optical devices used in reconnaissance, can suffer serious harm and have their effectiveness impaired by exposure to the forces of nature or synthetic destructive agents.
A variety of vehicles can benefit from the protection afforded by the covers of the present invention. Examples are: civil and military aircraft (fixed wing and helicopters) and terrestrial vehicles such as trucks, buses and automobiles. Military vehicles in particular are often subjected to harsh conditions for prolonged periods under stresses not normally experienced by civil aircraft. The severe conditions encountered in desert terrains provide a good example of the kinds of environmental hazards that vehicles, and especially military vehicles such as tanks, personnel carriers, fixed-wing aircraft and helicopters, may encounter for sustained periods of time. Military vehicles may also be the targets of chemical agents designed to impair or destroy their effectiveness by damaging surfaces, instruments or components necessary for their proper and efficient operation.
The prior art discloses several attempts that have been made to deal with the risks posed to vehicles, especially aircraft, by environmental hazards. One approach calls for applying a heat-shrinkable plastic wrap to the contours of the aircraft's exterior surface and heating the wrap to fit snugly against the surface to be protected. This approach is described in U.S. Pat. No. 4,763,783. According to this usage, a wrap can be selected that is impermeable to ultraviolet radiation as well as to seawater, rain and dirt. Similar technology may be applied to other vehicles, such as boats, as illustrated in U.S. Pat. No. 4,247,509. The coverings described in these two methods are not reusable, but are to be discarded after each use.
To similar effect is an airtight envelope taught in U.S. Pat. No. 3,815,650. The envelope is made of a flexible material, impermeable to dirt and moisture. The seams of the envelope are hermetically sealed and the space between the hermetically sealed envelope and the vehicle body may be evacuated with a pump. The envelope may thus be made to conform to the vehicle exterior and fit tightly against it. Alternatively, an inert gas such as nitrogen may be pumped into the envelope after evacuation to create an air cushion between the envelope and the vehicle body as well as a clean environment free of corrosive agents.
A reusable protective covering for aircraft has been devised which uses pads of protective foam, as described in U.S. Pat. No. 4,598,883. In this apparatus, protective foam is laid on horizontal surfaces, such as the wings of an airplane, and secured with straps encircling the wing. The straps are to be drawn tightly enough against the foam to compress the foam directly beneath the strap to create an air space between the surface of the wing and the pad. The air spaces thus formed are intended to prevent accumulation of moisture underneath the reusable protective cover and alleviate any damage that might be wrought thereby.
Finally, reusable protective coverings can be molded out of plastic with precision to adhere closely to the surface of an aircraft body or an appendage, such as a radome or a missile. U.S. Pat. No. 4,436,569. Protective coverings of this nature are particularly useful for preventing damage to delicate electronic components, such as radar equipment or the guidance avionics in the nose of a rocket or missile, from rain erosion while an airplane is in high-speed flight.
Other protective means for parking, storage or shipment of vehicles include canvas wraps or plastic sheeting. While these and the other previously described means for protecting vehicles, especially military vehicles, provide adequate means of protection against some hazards, it is desirable to provide protective coverings which are effective against a wider range of hazards. For example, some covers described above are ineffective against impact from hail. Others would be ineffective against agents to be expected during a chemical attack by enemy forces or harmful airborne or waterborne pollution. Some are ineffective against wind-blown sand and dirt and possess no means to prevent damage to the vehicle surface from chafing, scratching or abrasion by such particulate matter that may lodge between the protective covering and the vehicle outer surface. It is also desirable to provide protective means which can be installed easily and swiftly by one or two crew, that are light of weight and easy to handle, and which require a minimum of storage space. It is also desirable to provide protective covering means capable of avoiding the build-up of heat to extremely high temperatures in desert and tropical climates.
The present invention overcomes many of the disadvantages of the above-described vehicle covers by providing hardside canopy covers for vehicle surfaces comprised of a molded polymer which conforms to the shape of the vehicle surface to be protected. The covers of the present invention can be installed in a relatively short period of time, by one or two people, and removal is just as expedient. The covers can be stacked for easy and compact storage. The covers of the present invention provide good protection from sand, dirt, dust, ultraviolet radiation (heat and deterioration), chemical damage (for example, acid rain and chemical munitions), and weather (wind, ice and hail, for example). The covers also provide an air space for thermal insulation against heat build-up in tropical or desert climates. Moreover, use of the present invention results in savings of time for installation, removal and storage, and savings on material costs in that the covers may be used and reused indefinitely. Fabrication costs are also extremely low.